1. Field of the Invention
The present invention relates to diagnostic ophthalmic compositions and a method of administering those compositions during routine eye examinations. In particular, the inventive compositions, which preferably contain a local anesthetic, a dye and a dilating agent, perform multiple functions, including: 1) anesthetizing the cornea to allow for pain relief, manipulation and the measurement of intraocular pressure ("IOP"), 2) dying the cornea to allow for the detection of pathology and the measurement of IOP, and 3) dilating the pupil to allow for examination of the optic nerve, macula, retina, retinal vasculature, and peripheral fundus ("dilated exam"). These compositions may also include a preservative, a wetting agent, a diluting agent, and/or buffers. The method of administering these ophthalmic compositions enables the physician to perform more efficient eye examinations. The compositions may also be used to perform similar functions prior to ophthalmic surgery.
2. Background
A routine eye examination typically consists of three basic components: 1) examination of the front structures of the eye; 2) measurement of IOP; and 3) examination of the optic nerve, macula, retina, retinal vasculature, and peripheral fundus (the "dilated fundus exam"). The current state of the art consists of sequentially administering multiple topical agents to a patient's eye in order to perform the multiple components of the examination. This sequence is described as follows:
First, a topical anesthetic agent, usually proparacaine or tetracaine, is applied to the eyes to anesthetize the cornea and allow for visualization and manipulation. Next, a fluorescein strip (or other acceptable dye) is applied to the tear film as a disclosing agent to reveal pathology, such as corneal abrasions or ulcers. The application of topical anesthesia and fluorescein is followed by the measurement of IOP by applanation tonometry, which is the method most commonly used by clinicians to measure IOP. After the cornea is examined and IOP is measured, a topical dilatipg agent is usually instilled to dilate the pupil, thereby permitting dilated fundus exam by direct and/or indirect ophthalmoscopy. The dilating agents used are typically sympathomemetic agents, parasympatholytic agents, or both. After instilling the dilating agent(s), the doctor and patient must wait approximately twenty minutes to allow for adequate pupillary dilation in order to conduct the dilated fundus exam (the "waiting time"). The waiting time is an extremely inefficient part of the routine eye examination according to the current state of the art.
Diagnostic ophthalmic compositions currently exist which combine some, but not all, of the above components to allow for some, but not all, of the necessary functions for a complete eye exam. For example, a combination of benoxinate hydrochloride (a topical anesthetic agent) and fluorescein sodium (a dye) is currently available (by Akom, Inc., of Decatur, Ill.). This combination provides anesthesia to the patient's eye and simultaneously stains the cornea to allow for corneal examination and IOP measurement. Another currently available combination anesthetic/dye is FLUORACAINE.RTM. solution, also by Akom, Inc. This combination agent includes proparacaine hydrochloride as the anesthetic and fluorescein sodium as the dye. However, even with the use of these currently available combination agents, after measuring IOP, according to the current state of the art, the doctor must still apply one or more dilating agents and allow for the waiting time to elapse before performing a dilated fundus examination.
Other formerly available combination agents combine two dilating agents, specifically a sympathomemetic agent and a parasympatholytic agent. For example, a combination of phenylephrine and tropicamide, and a combination of tropicamide and hydroxyamphetamine were formerly available. Notwithstanding all of the above-mentioned commercially available combination agents, at least two distinct compositions are required according to the current state of the art for a complete eye examination--a combination anesthetic-dye drop applied before IOP measurement, and a dilating agent or combination dilating agent applied after IOP measurement. Thus, with the current state of the art, multiple drops are still required and the inefficient waiting time is still a necessary part of the examination to allow for sufficient pupillary dilation. It would be advantageous to eliminate the multiple eye drops necessary for a complete eye examination, as well as provide a method of administration which eliminates or greatly reduces the waiting time, thereby maximizing efficiency and minimizing patent discomfort.